Lighting can be classified as regular lighting and spot lighting. The former is for a wide lighting of a large area, while the latter is for concentrated lighting in a small, spot-like area.
For example, the wide lighting for a large area includes street lamps, post lamps in for example a park, or ceiling mounted pendant lighting. The purpose of the wide lighting is to illuminate the whole area with the least number of lighting devices.
Contrary to the regular lighting, the spot lighting is to condense light beam onto a specific spot or article to distinguish the spot or the article. For example, firstly, an exhibition lamp that is provided for the purposes of exhibition must condense the light spot on an exhibited article to distinguishably show the article. Secondly, spot lighting can be used for interior decoration for the modern interior decoration, except the aspect of hardware decoration, include an aspect of visual impression that is presented by lighting inside the house, of which the most commonly known measure is to condense and project light on for example a wall, an ornamentation or a dinning table so as to provide excellent visual and lighting effect with the combination of hardware decoration and the lighting.
However, some of the conventional lighting devices are not provided with the function of light condensation and/or focusing and most of the conventional lighting devices are not of the feature of focus adjustability. The former drawback make the use of the lighting device inconvenience or even impractical, while the latter drawback causes a situation of out of focusing of the projecting light on an irradiated article for the distance between the light source and the irradiated article can be various and cannot be accommodated by the lighting if no focus adjustability can be available.
Thus, the present invention is aimed to overcome the above discussed drawbacks.